There has been used a water pressure transfer method for decorating a complicated three-dimensional surface of an article. Typically, this water pressure transfer method is the one in which a transfer film having a predetermined water-insoluble print pattern applied onto a water-soluble film is floated on a water surface within a transfer tub and made wet with the water and an article (a transferred body or a body to be pattern-transferred) is immersed into the water within the transfer tub while it contacts the transfer film whereby the print pattern of the transfer film is transferred onto the surface of the article by using the water pressure to thereby form a decorative layer.
In general, since the water pressure transfer film is stored in a roll form with the print pattern printed and dried on the water soluble film, the print pattern is in a dry state while it have an adhesion lost and therefore it is required to coat a solvent such as an activator or a thinner to the print pattern so as to get a wet state similar to a state of the ink immediately after being printed (a state where it has an adhesion), which is generally called an activation treatment. In order to provide mechanical or chemical surface protection function such as wear resistance, solvent resistance, medicine resistance, weather resistance, etc. to the decorative layer formed on the surface of the article by the water pressure transfer, a transparent surface protection layer (topcoat layer) is generally formed on the top of the decorative layer.
Such a surface protection layer is formed either by being applied by spray means or by water pressure transfer means etc., separately from the decorative layer or by water pressure transfer method at the same time when the decorative layer is formed by water pressure transfer (see Patent Documents 1 and 2). In either of these cases, since the decorative layer itself has no surface protection function, the surface protection layer separate from the decorative layer is required. However, since the method of separately forming the surface protection layer and the decorative layer requires two operations of decoration and surface protection, the effectiveness in operation gets lower and since the method of simultaneously forming the surface protection layer and the decorative layer requires a water pressure transfer film of complicated construction. Thus, any of the methods cannot disadvantageously provide the decorative layer having the protected surface in an inexpensive manner.
Meantime, the inventors have proposed the invention of a method of transferring a decorative layer under water pressure while the wear resistance, the solvent resistance etc. are imparted to the decorative layer itself and this invention has been applied for patent (see Patent Documents 3 through 5). According to this method, an ultraviolet ray hardening resin composite containing a non-solvent type activation ingredient such as a photo-polymerization monomer is applied onto a dried print pattern of a water pressure transfer film whereby the adhesion of the print pattern is recovered by the activation ingredient of the ultraviolet ray hardening resin composite. Also, since the print pattern is transferred onto the objective body under water pressure in the state where the ultraviolet ray hardening resin composite permeates the whole print pattern, when the ultraviolet ray hardening resin composite is hardened by radiation of ultraviolet rays, the decorative layer formed by the print pattern just gets the state where the ultraviolet ray hardenability is imparted thereto and therefore the chemical and mechanical surface protection function such as the solvent resistance, the wear resistance etc. are imparted to the decorative layer itself.
In order to integrally combine the print pattern and the ultraviolet ray hardening resin composite by allowing the ultraviolet ray hardening resin composite to permeate the print pattern for recovering the adhesion of the dried print pattern and imparting the ultraviolet ray hardenability to the print pattern by applying the ultraviolet ray hardening resin composite to the water pressure transfer film, the ultraviolet ray hardening resin composite requires the viscosity relatively lower enough for the resin composite to be able to uniformly permeate the whole print pattern once dried and cured and the ink solubility being able to dissolve the ink and recover the adhesion thereof and this ultraviolet ray hardening resin composite is desirably applied to the print pattern in a predetermined amount of application. If the viscosity of the ultraviolet ray hardening resin composite is too high, then this ultraviolet ray hardening resin composite cannot permeate the whole print pattern in a proper amount, if the ink solubility of the ultraviolet ray hardening resin composite is too low, then the adhesion of the print pattern of the state where it is dried and cured cannot be recovered, and the amount of application of the ultraviolet ray hardening resin composite is too low, then the ultraviolet ray hardening resin composite cannot reach the surface of the print pattern (an outer face of the print pattern after transferred).
Further, if the viscosity of the ultraviolet ray hardening resin composite is too low and the amount of application thereof is too high, the print pattern is invited to be disturbed whereby there appears the phenomena where the pattern gets obscure or disordered.
Thus, the ultraviolet ray hardening resin composite requires a predetermined viscosity, ink solubility and amount of application in order to recover the adhesion of the dried print pattern and allow the ultraviolet ray hardening resin composite to permeate the print pattern so as to be integrally combined or mixed with the print pattern. What is meant by “integral combination of the ultraviolet ray hardening resin composite” is not for the ultraviolet ray hardening resin composite to be partially combined with the print pattern, but for the ultraviolet ray hardening resin composite to be wholly combined with the print pattern preferably in a uniformly combined manner. If the ultraviolet ray hardening resin composite is combined with the print pattern only on the side of application of the resin composite, but does not reach the outer surface of the print pattern after transferred, the surface protection function such as the solvent resistance, etc. cannot be imparted to the surface of the decorative layer, which is the outermost surface of the decorative layer.
In the invention of the aforementioned method proposed by the inventors, it is disclosed to use what is commercially available under “UV MAT-000 MEDIUM”, the trade name of UV type screen ink from TEIKOKU INK MANUFACTURE CO., LTD., Japan or what is commercially available under the name “UV PAL-000 MEDIUM”, the trade name of UV type screen ink from TEIKOKU INK MANUFACTURE CO., LTD., Japan as the ultraviolet ray hardening resin composite suitable for recovering the adhesion of the print pattern and for integrally combining the ultraviolet ray hardening resin composite with the print patter by permeation of the ultraviolet ray hardening resin composite into the whole print pattern. These composites are commercially available for wide use and can recover the adhesion of the dried print pattern and impart the ultraviolet ray hardenability to the print pattern by its permeation into the whole print pattern to a certain extent. Thus, these ultraviolet ray hardening resin composites for wide use can be applied just to a water pressure transfer of low or middle grade in which a pattern just like grain should just be attached. These ultraviolet ray hardening resin composites for wide use cannot be fully applied to a water pressure transfer of high or super-high grade in which a minute design quality such as true tree feeling required for decoration in a car interior article. In addition thereto, these ultraviolet ray hardening resin composites cannot be fully applied to various transfer films having huge accumulation of the past with respect to the elements of the ink such as the kind of ink or the shade to be used for the print pattern and there remain the problems in compatibility and conformity with various equipment used in the conventional water pressure transfer processing lines.
These commercially available ultraviolet ray hardening resin composites contain at least photo-polymerization pre-polymer, photo-polymerization monomer and optical initiator and are manufactured as products for various uses such as inks, coating materials, adhesives or the likes by preparing them and adding other ingredients in some cases. These commercially available ultraviolet ray hardening resin composites were not such products as were manufactured for intentional use in which the resin composites permeate the whole ink once dried and cured so as to be integrally combined with the print pattern and is hardened together with the ink after the ultraviolet ray is radiated as if the ultraviolet ray hardenability is imparted to the ink. In the embodiment disclosed in the aforementioned patent documents, what enables the recovery of the adhesion of the ink and the provision of the ultraviolet ray hardenability to the print pattern is found out of the conventional products of other uses and are used compromisingly.
The inventors make various preparations while photo-polymerization pre-polymer, photo-polymerization monomer etc. change in their kinds and combinations when they looked for a novel ultraviolet ray hardening resin composite most suitable as a coating agent for a water pressure transfer film having a viscosity relatively low enough to be able to uniformly permeate the whole print pattern once dried and cured and an ink solubility enough to recover the adhesion of the ink by dissolving it and with the result of repetitive tests, they find that there are required a predetermined viscosity and a predetermined ink solubility for the ultraviolet ray hardening resin composite suitable for the coating agent for the water pressure transfer film and that such settings as the selection of the photo-polymerization monomer are much important for it.
More particularly, the photo-polymerization monomer has the following requirements;    (1) The photo-polymerization monomer itself has low viscosity in order to obtain the proper viscosity of the ultraviolet ray hardening resin composite having the photo-polymerization monomer added thereto.    (2) The photo-polymerization monomer requires the solvent power to the photo-polymerization polymer essential for the physical property of the finished coating film tending to have a high viscosity.    (3) The photo-polymerization monomer requires the solvent power to the ink of the print pattern.    (4) The photo-polymerization monomer itself also has a good hardenability when the ultraviolet ray is irradiated.    (5) The photo-polymerization monomer has a good adhesion to ABS resin, PC materials etc. used as base materials of a water pressure transfer article in many cases.    (6) The photo-polymerization monomer requires a lower contractility when cured and a smoothness and also has a transparency maintained.
Thus, it is found that the coating agent for the water pressure transfer film comprises an ultraviolet ray hardening resin composite containing the photo-polymerization monomer meeting the aforementioned requirements.    [Patent Document 1] JP4-197699A    [Patent Document 2] JP2003-200698A    [Patent Document 3] JP Application No. 2003-409874 specification    [Patent Document 4] JP2005-14604A    [Patent Document 5] WO2004/108434